28) air can be considered a mixture. which statement describe air? a) air contains a fixed ratio of atoms. b) the components of air separate into visible layers. c) the components of air can be separated by chemical means. d) the exact mixture of components varies from point to point.

The answer is D. correctly

Non metal is an element or substance that is not a metal metal is a solid material that is typically hard, shiny, malleable, fusible, and ductile, with good electrical and thermal conductivitymetalloid is an element (e.g., germanium or silicon) whose properties are intermediate between those of metals and solid nonmetals. they are electrical semiconductors.